This invention relates generally to video signal processing and more particularly to restricting access to such video signals based on associated access restriction data.
Unauthorized copying of copyrighted works is, unfortunately, very prevalent. Such unauthorized copying ranges from simple copying of a few pages of a copyrighted book to widespread distribution of millions of dollars worth of illegally copied movies, compact discs, and other entertainment medium.
With the advent of digital videodiscs (DVD) the illegal copying of DVDs is of great concern to content companies (i.e., the companies owning the copyrighted work recorded on the DVDs). To protect the copyrighted works, content companies are demanding that DVD producers incorporate a security mechanism to prevent unauthorized copying. One such recommended security mechanism is currently being used in conjunction with videocassette recorders and was developed by Macrovision.
The Macrovision technique (hereinafter referred to as Macrovision) essentially places additional coding in the vertical blanking interval and/or horizontal sync signals of a video stream provided to a television for display. The television can filter out the additional coding with negligible video effects, but a video cassette record (VCR) is not able to filter out the additional coding, thereby preventing the VCR from making quality copies.
While Macrovision prevents VCRs from making quality copies, it does not prevent unauthorized copying for a VCR, or any other video source (including a DVD player) coupled to a personal computer (PC). As is generally known, a PC may be equipped with an analog video decoder, such as one contained in the All-in-Wonder manufactured and distributed by ATI International, which converts an analog video signal into a digital video data stream. The analog video stream may have been originated by a video source such as a DVD player, a VCR, television broadcast, cable broadcast, etc. The analog-to-digital conversion (ADC) of the analog video stream typically removes the Macrovision encoding. As such, a DVD player, or other video source, that sources an analog video stream to a PC may have the copyrighted work copied without the Macrovision encoding due to the ADC. Such unauthorized copying is unacceptable to content providers.
Therefore, a need exists for a method and apparatus that restricts usage of video signals in accordance with associated access restriction data, such as Macrovision.